Communication services, whether land-line telecommunication, cellular telecommunication, or other radiocommunication services, are offered through the use of automated equipment. Computing services, database services, and various financial services are other examples of automated services. These and other automated services are offered to subscribers by service providers. Typically, subscribers utilize such services through user equipment, and service providers establish and maintain infrastructures which cooperate with the user equipment to provide resources to the subscribers.
The providers of automated services often need to insure that their services are being provided only to legitimate subscribers. When the resources are valuable, such as when communication is involved, piracy of the services can deprive the service provider of revenues, waste scarce resources on users not entitled to receive the resources, reduce availability of resources for legitimate subscribers, and generally increase costs for legitimate subscribers. In other situations, such as in connection with database and financial services, the offered resources are of a sensitive nature wherein serious damage can result from unauthorized tampering. In order to insure that only legitimate subscribers use available resources, service providers often employ systems to authenticate the users. In accordance with one authenticating system, the service provider supplies both the infrastructure equipment and all the user equipment. The service provider may design the various parts of this equipment to cooperate with one another in accordance with proprietary design parameters. While this system may be effective with a small number of users, legal and economic factors cause it to fail as the number of users increases to mass market proportions. As the number of users grows, additional equipment suppliers desire to serve the marketplace, the design parameters tend to become widely known, and "pirate" equipment tends to appear. Unauthorized users can then gain access to the service through the use of pirate equipment.
Other systems cause the users to take particular actions to gain access to the service. For example, computer and database resources often require users to supply passwords before access to the service is granted. Financial services often require users to supply personal identification numbers (PINs) before access is granted. However, such passwords and PINs are not effective in authenticating users. When passwords and PINs are configured so that they can be easily remembered, they are easily discovered by potential pirates. When passwords and PINs are more complex, legitimate subscribers tend to write them down where they become vulnerable to pirates.
Other systems require legitimate users to carry devices which include complex and occasionally encrypted codes that serve to identify the users. Such devices are often used with PINs to protect against theft of the device. When the devices include encrypted codes, the service providers typically provide elaborate key management procedures making the service more burdensome and driving up the costs for all legitimate users. Furthermore, requiring users to carry devices to access a service is an unwanted burden in many situations.